A problem that often arises for drivers of vehicles is the blinding effect of sunlight through the windshield and windows of their vehicles. The visors positioned near the top of the windshield have been utilized as one solution to the problem of blinding sunlight. Another method of reducing sunlight glare is the use of a tinted belt-filter layer along the top portion of the windshield. However, a tinted layer coated only on the top portion of the windshield is not effective for reducing the glare through the rest of the windshield. Also, the sunlight entering through the top portion of the windshield can be blocked entirely by the blind visor. Neither device reduces sunlight in the middle portion (i.e., driver's field of view) of the windshield, which sometimes can result in significant hazardous driving conditions.
Hazardous driving conditions can become even more severe during times of high traffic for those who drive east in the morning and west in the afternoon, when the sun shines directly into drivers' eyes from a low angle above the horizon. As neither visor nor tinted layer in current vehicles reduces the direct sunlight in the middle portion of the windshield, drivers can feel a strong sting from the sun's glare. A driver may be inclined to avoid looking forward at the sun even while wearing sunglasses. Current state of the art general use sunglasses are not designed for looking at the sun directly. In addition, it is inconvenient for drivers wearing prescription glasses to wear sunglasses. Drivers may try to look slightly sideways or sit up tall and look downward to alleviate the problem, although this is inadequate as the sun's glare is prevalent throughout the field of view. As the clarity of the front view is greatly reduced, drivers usually have to slow down dramatically, compounding the east bound traffic in the morning and west bound traffic in the evening. This results in wasted energy resources and driver's time, and can contribute to green gas generation and thus global warming.
U.S. Pat. No. 2,112,726 to Kempt et al. describes a device to install a glare screen either in between the windshield and visor or in combination with a visor to protect the driver from the sun's direct rays, or headlights, diffused or reflected rays. U.S. Pat. No. 4,130,317 to Lai describes an improved clamping device for the holding of a sun-reducing glass in an automobile. Both patents only teach installing a sun glare-reducing glass, and do not address the glare screen itself. The transparent or translucent glare-reducing glasses recommended by Kempt et al. do reduce sunlight to a certain degree. However, due to its transmission invariability, Kempt's glasses either insufficiently reduce or reduce too much sunlight depending on the materials the glasses are composed of.
Therefore, there is a need for a device with adjustable attenuation of sunlight for automobiles. When it is in use, it would be preferable for a device to block the proper amount of sunlight so that the glare suffered by drivers will be reduced and they will be able to see the road conditions clearly and comfortably. In addition, as the intensity of sunlight viewed by the driver varies depending on the time of day, weather conditions, the time of the year, and road direction change (for example, the sun may appear directly in front, to the left, or to right when the road curves), it is desirable that the attenuation of sunlight is automatically adjusted so that the driver sees relatively constant light and driving visibility is less affected.